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Drug War Awaits Attack of Killer Fungus

Dr. David C. Sands holds out a clear plastic petri dish filled with a white fuzzy fungus growing across the bottom. This substance, he believes, is the key to ending much of the world's production of illicit drugs.

Members of Congress also believe that Dr. Sands and other researchers may be on to a powerful and environmentally safe method of killing not only coca plants, but also marijuana and poppy plants. The members have asked the government of Colombia to test a strain of Fusarium oxysporum over the next two years. If it proves effective, the disease will be sprayed on vast fields of coca plants there, and experts say it could wipe out much of the coca crop within a year.

The research holds such promise that officials at Montana State University ended it two years ago, fearing it could make the university a target of drug cartels. But the technique had already been developed.

Others are not sure that fusarium will be effective against the the cartels. ''Efficacy is high on my list of concerns,'' said Eric Rosenquist, a United States Department of Agriculture official involved with international research programs. ''You can put a lot of energy into this and get nothing out in the end.'' Mr. Rosenquist said a naturally occurring fusarium coca virus in Peru had killed only 40 percent of the crop there.

An attack on coca plants may be only a first salvo in the attack of the fusarium fungus. Dr. Sands and others believe that the use of fungal disease is an ideal way to kill a broad range of undesirable plants. Research on fusarium has been under way for years, and Dr. Sands and other scientists say the research is about to usher in an era of effective and environmentally safe controls that would be alternatives to chemical herbicides and genetically modified organisms.

Biological controls, the use of a pest's enemies against it, are old: centuries ago, the Chinese built bridges between trees so predatory ants could find and destroy aphids. But biological control is not yet proven as a viable alternative to chemicals. Most diseases and predatory insects, for example, are not especially deadly; they ''farm'' a plant, attacking it but not wiping it out, so they can keep consuming it. ''They live in total coexistence, like real estate agents,'' Dr. Sands said. ''They take a percentage. If they took too much they would be out of business.''

But some diseases are especially virulent, wiping out most or all of the host. Phytophtora, a fungus that destroyed potatoes in 19th-century Ireland and caused the great famine there, is one. Fusarium, Dr. Sands said, is another of the ''Attila the Hun'' diseases, and there are strains of fusarium for virtually every cultivated plant and many wild ones.

A plant pathologist, Dr. Sands came to the field of bioherbicides in his search for a way to treat exotic plants from Asia that run rampant through Western range land because they are unchecked by native enemies. Some diseases found in Montana are being tested on these weeds. But a much more effective approach, Dr. Sands said, may be to bring back the fungal diseases that the weeds evolved with in Central Asia and elsewhere and use them as herbicides.

He has had collaborators scouring Kazakhstan and Russia for diseases that evolved with two especially difficult species, spotted knapweed and leafy spurge, and some have been shipped to the United States where they remain in a containment facility in Maryland awaiting approval to be used in testing.

In 1987, while working with weeds, Dr. Sands got a call from the department of agriculture. Worried about a revolution in Peru, Coca-Cola had established a coca plantation in Hawaii to assure a supply of the plant for its soft drinks. (The stimulating components of the plant are not included in the product.)

When the plantation was abandoned, the department used the plants to test herbicides that might be used in the drug war. But something killed many of the plants in a control plot that was not being sprayed. Dr. Sands discovered that it was a strain of fusarium.

Dr. Sands cultured the fungus and spread it as granules on a three-acre plot. It killed nearly all of the coca plants.

Fusarium is especially virulent on plants that dominate a landscape, he said. Dutch elm disease and chestnut blight are both fungal diseases similar to fusarium. They destroyed trees across America because those trees were the only ones that many cities planted.

While Dr. Sands believes that importing diseases can be an effective approach to combating exotic weeds in Montana, officials in Colombia say they will use an indigenous fungus, a strategy Dr. Sands also advocates, because coca is a native plant. But because politics as well as biology is involved, the outcome in Colombia remains in question.

Conservationists generally favor substitutes for chemicals in killing weeds, but some are not sure that de facto biological warfare is the answer. They worry about ''mission drift''; a disease may start as an effective enemy of coca but somehow change hosts and kill important nontarget plants, like bananas, or attack wild relatives of the coca plant and threaten biodiversity.

Dr. Peter Stiling, a professor of biology at the University of South Florida who has studied introduced species, says possible unintended effects have not been sufficiently examined. ''I am not prepared to come down on one side of the fence.'' Dr. Stiling said. ''But I think we should be careful. It's difficult enough to find the nontarget effects of insects, and it's even more difficult for nontarget effects of fungi and bacteria.''

Such problems are often subtle at first and might not be found for a long time, Dr. Stiling said. A study in Oregon has indicated that the use of Btk, a bacterial pesticide for control of the western spruce budworm, may have reduced the abundance and diversity of butterfly larvae.

''There are 500 people working on fusarium,'' Dr. Sands responded, ''and we don't see it changing its host species.''

So far, no environmental problems have been blamed on fusarium, largely because it has not been widely used in the United States.,

The use of fungal disease as a herbicide was studied before by the Agricultural Research Service, but the agency determined that it wasn't viable as a biological control primarily because it required a great deal of the product to cover the vast areas involved.

To make fusarium economical, Dr. Sands and other researchers have discovered they can use a native grass seed to culture the fungus. In a patented process, they spray fusarium on the seed and drop it; when it hits the ground the fungus multiplies. Once the fungus kills the coca plants, the theory goes, the grass seed or whatever seed officials choose to use, takes over for the dead plants.

What's more, the fungus lasts in the soil. ''They kill and they survive the nongrowing season perhaps for as long as five years,'' Dr. Sands said.

Another advantage to fungal defoliants is that while chemicals must be sprayed on coca plants from very low altitudes during daylight, fusarium can be dropped from thousands of feet above the fields at night.

Although the university ended the fungus research, Dr. Sands said that others could easily follow his formula for making fungus-based bioherbicides.

Culturing fungus is fairly simple and can be taught in a couple of weeks, he said.

The coca producers could respond with a fungicide or disease-resistant plants, but Dr. Sands said that could take many years.